Developing Functional (Design) Evaluation Requirements for Cable Median Barriers

摘要

There has been increased use of cable median barriers in recent years to address the growing problemof cross median crashes despite limited current guidance on effective designs and placement forvarying median configurations. Research has discovered that cable median barrier effectiveness issensitive to slope effects. Vehicle dynamics analysis was found to provide a means to understandvehicle trajectories (or traces) for particular cross median events. By combining individual traces fordifferent vehicles, road departurs, and median conditions, it was possible to determine the limits foroverride and underride for any median configuration and to use these to evaluate the potentialeffectiveness for any given barrier design. Further efforts, described in this paper, developedcomposite limits that are not median configuration biased. These limits are shown to have usefulnessfor specific sets of median area and maximum side slope conditions encountered. These are believedto offer usefulness to the design of new cable median barrier systems, consideration of the relativeapplicability of existing barriers for particular applications, and even a potential means to increase theconfidence that a given barrier application will provide the same level of crashworthiness asdetermined in testing. The information generated in this effort is believed to provide a robust basis forthe development of improved (simplified) guidelines for cable median barrier design and placement.